New Weight Loss Injections: What They Are and How to Track Your Journey

The injectable medicines currently prescribed for weight management belong to a class that works on appetite-regulating pathways in the body. Mounjaro (tirzepatide) acts on both GLP-1 and GIP receptors, while Wegovy (semaglutide) acts on GLP-1 receptors. Both are once-weekly injections, and both are prescription-only medicines — meaning a prescriber or doctor must decide whether they are appropriate for you.

What about newer injections like retatrutide?

Retatrutide is among the next wave of injectable medicines being investigated in clinical trials as of 2024 and 2025. It acts on three receptors — GLP-1, GIP, and glucagon — and has attracted attention in research settings. However, it is not yet an approved or commercially available medicine in most countries. Anyone who has been told about a weight loss injection by their prescriber should refer directly to the information their prescriber or healthcare professional has provided, as what is available varies by country and clinical context.

Side effects commonly reported with injectable weight loss medicines

People prescribed these medicines commonly report gastrointestinal side effects, including nausea, constipation, diarrhoea, indigestion, and occasionally vomiting — particularly in the early weeks or after a dose adjustment. Fatigue, headache, and injection-site reactions are also frequently mentioned. These effects are generally most noticeable at the start of treatment or after a dose change, and many people find they ease over time.

It is important to note that side effects vary between individuals. If you experience anything severe, persistent, or worrying, contact your healthcare professional promptly rather than waiting. Any side effect worth noting should also be reported to your national pharmacovigilance scheme (such as the UK's Yellow Card scheme or the equivalent in your country), as well as discussed with your prescriber.

For a broader overview of how these medicines work and what people on them commonly experience, the weight loss injections guide covers the key facts in one place. You may also find it useful to read about whether the new weight loss injections are considered safe, which looks at the safety profile in more detail.

Whichever injectable medicine you have been prescribed, keeping accurate records makes a real difference — both to your own sense of progress and to the conversations you have with your prescriber.

GLP Trackr's injection-site tracking and rotation feature is particularly useful here. Each time you inject, you can log the site — abdomen, thigh, or upper arm — and the app keeps a history of your rotation so you always know where your next injection should go. Rotating sites consistently is something prescribers and patient information leaflets typically recommend, and having it tracked automatically removes one more thing to remember.

Alongside site tracking, the app's side-effect logging lets you record how you feel in the days after each injection. Over time, patterns become visible — for example, whether nausea tends to peak at a particular point in your weekly cycle — and that information can be genuinely useful to bring to a prescriber appointment. The doctor report feature lets you share a clear summary of your logged data with your healthcare team.

GLP Trackr also helps you stay consistent with dose reminders, so a weekly injection is never accidentally missed or delayed.

A note on medical decisions: GLP Trackr is a tracking and journaling tool, not a clinical service. Any questions about your dose, your injection schedule, or whether a new medicine might be right for you should always be directed to your prescriber or doctor — they know your full history and are best placed to advise you.

If you are curious about obtaining or accessing one of these medicines, the guide to accessing weight loss injections explains the general process of how prescription medicines are obtained through a prescriber and registered pharmacy.

Ready to bring your whole injection journey into one place? Download GLP Trackr on the App Store or Google Play — your first 7 days are completely free.